This application is a 371 of PCT/EP02/13051 filed Nov. 21, 2002.
This invention relates generally to the field of oleochemistry and, more particularly, to a process for the production of technical oleic acid methyl esters with a low stearic acid methyl ester content by multiple fractionation of palm kernel oil fatty acid methyl ester.
Unsaturated fatty alcohols with iodine values in the range from 80 to 100 are valuable raw materials for the production of detergents and cosmetics. These compounds are synthesized by reduction of the corresponding technical oleic acid methyl esters which, because of their natural origin, always contain saturated homologs. However, in order to guarantee satisfactory low-temperature behavior, the content of stearic acid methyl ester in these starting materials has to be below 2% by weight. To guarantee this, the fatty acids on which the esters are based are normally subjected to separation of wetting agent (“rolling-up”) or to solvent crystallization (Emersol process) which, on the one hand, is expensive on equipment and, on the other hand, makes the simpler method of producing the esters by transesterification of the triglycerides impossible. Alternatively, fractional crystallization could also be carried out at the alcohol stage (WO 98/42646, Cognis) although this would also involve an additional processing step and is therefore undesirable.
Accordingly, the problem addressed by the present invention was to find an alternative process for the production of oleic acid methyl esters with methyl stearate contents of or below 2% by weight which would not be attended by any of the disadvantages mentioned above. In particular, the process would not require additional crystallization steps and could be operated continuously. Preferably, the process would provide oleic acid methyl esters in a purity of at least 75% by weight.